"I'm going to keep the burden on the upper-income people the same as it is today," the Republican presidential nominee-in-waiting said as he campaigned across Pennsylvania on Tax Day. "I know Democrats will say it day in and day out, 'They are for tax cuts for the rich,' he said, mimicking his rivals. "No,'" he added firmly.

By contrast, Romney said Obama wants to raise taxes, a step the Republican said would hamper job creation.

Unlike Romney and most Republicans, the president wants to allow existing Bush-era tax cuts to expire at the end of the year for those at upper incomes.

As he sought to parry the inevitable Democratic accusations, Romney also tackled a second, if unspoken concern, a perception that he has difficulty establishing rapport with middle-class voters.

To that end, his campaign arranged an outdoor event in a Pittsburgh suburb at which the wealthy former businessman-turned-politician and eight area residents sat amicably around a picnic table and talked about economic issues.

There was one fleeting moment of awkwardness, when Romney guessed that a plate of cookies set out on the table were from "a local 7-Eleven bakery or whatever," instead of a local firm, Bethel Bakery.

But Jason Thomas, one of the participants, later told reporters: "I thought he was likable person ... I will personally go on record and say he doesn't seem out of touch. He was asking us what our concerns were and we tried our best to represent our concerns, the concerns for our children, and a lot of our friends and family as well."

Romney so far has provided only a few details of the ambitious program of tax reform he says he will propose if he wins the White House.

He favors extending all the Bush-era tax cuts that are set to expire at the end of the year, and has said he wants to cut rates an additional 20 percent across the board.

Romney has also said he would reduce or eliminate some common tax breaks used by the wealthy to make up some of the revenue that would be lost.

But he has yet to provide much additional information, or even define what he means by "wealthy."

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In his conversation with Thomas and others around the picnic table, Romney emphasized that middle-income Americans would benefit from his proposal to eliminate taxes on interest, dividends or capital gains for anyone earning $250,000 or less.

When another person at the table, Kelly Wassel, expressed concern that the $500 per-child tax credit might expire at the end of the year, his response sounded like he might allow that to happen. "I would actually like to reshape the entire tax system, all right, that is what I'd like to do, and to simplify the system as opposed to all these little ... baby steps," as she nodded without protest.

Romney set off a controversy over the weekend when he was overheard telling donors he might want to abolish the tax break for mortgages on second homes, or perhaps do away with state and property tax deductions for the wealthy.

For the second day in a row, aides sought to dampen the controversy while he avoided it.

On a conference call with reporters where surrogates criticized Obama for being vague about his own proposals, Rep. John Campbell of California turned aside a question about possible parallels to Romney.

"There's a bunch of choices and there's a bunch of ideas, and frankly, which specific one you choose isn't that critical at this juncture," he said.